Discussion on the sea–land telluric current vector and its continuity during a geomagnetic storm based on coastal stations in China and Canada

摘要

The sea-land telluric current vector and its continuity during two geomagnetic storms are discussed using observation data of 13 geoelectric field stations within 100?km of the coastline in China and 5 similar stations in Canada. The results show that the amplitude of the geoelectric field varies up to 300–2600?mV/km at high latitudes and in the range 100–300?mV/km at low latitudes, below 100?mV/km at the middle latitudes, when the two geoelectric storms loading. The energy spectra of geoelectric field at RES in Canada is found to be concentrated in 16–48?min, and at CHL in China concentrated in 64–128?min. The telluric current flows directly to sea from the coastal land, except the two land-type stations with particular electrical structures. The sea-land current continuity model which was set up based on geological and geophysical data to deduce vertical circulation of current channels in continental and marginal seas area, which can explain the different current orientations in different regions. Our detailed analysis show that the direction of telluric current of Island stations is related to the deposition and river erosion and controlled by ocean currents during monsoon, are also included by the model. At last, the sea-land telluric current continuity model provides well understanding for the constraints of conductivity on the sea-land interface.